Part of the John Deere Repair Manuals.
This is the John Deere factory repair manual for the 6120, 6220, 6320, 6420, 6120L, 6220L, 6320L, 6420L and 6520L tractors. At 1,904 pages it covers every system you will pull apart on these machines: engine removal and reinstall, all four transmission options the 6020 series came with (SyncroPlus, Power Reverser, AutoPowr/IVT and PowrQuad/AutoQuad), the drive train from U-joint shafts to final drives, hydrostatic steering, hydraulic pump and rock shaft, the full electrical system with wiring harness diagrams, and the cab with air conditioning. Factory torque specs, adjustment dimensions and test pressures are listed throughout so you torque every fastener to spec on the first pass.
What's Inside This John Deere 6120-6520L Repair Manual
| System | Pages | Key Topics |
|---|---|---|
| Safety | Safety Measures | |
| General Information | Specifications, Tune-Up, Predelivery Inspection | |
| Engine | Installing and Removing Engine Components | |
| Fuel, Air Intake, Cooling and Exhaust | Speed Control, Fuel System, Air Intake System, Cooling System, Cold-Weather Starting Aid, Exhaust System | |
| Electrical System | Connectors, Wiring Harnesses, Charging Circuit, Starter Motor Circuit, Fuses/Relays/Switches, Monitoring Systems, Electrical Components | |
| SyncroPlus Transmission | Installing and Removing Components, Transmission Shift Controls, Perma Clutch II Module, Gear Transmission | |
| Power Reverser Transmission | Installing and Removing Components, Transmission Shift Controls, Power Reverser Module, Gear Transmission | |
| AutoPowr/IVT Transmission | Installing and Removing Components, Transmission Shift Controls | |
| PowrQuad/PowrQuad Plus/AutoQuad Transmissions | Installing and Removing Components, Shift Controls, PowrQuad Module, Creeper Transmission, Option Transmission, Range Transmission | |
| Drive Systems | U-Jointed Shafts and Torsion Damper, Front-Wheel Drive Clutch, Differential, Hydraulic Pump Drive, Final Drives, Rear PTO, Front PTO, Front Implement Drive | |
| Steering and Brakes | Hydrostatic Steering, Steering Cylinder, Brake Valve, Rear Brakes, AutoTrac | |
| Hydraulic System | Controls, Hydraulic Pump and Charge Oil Pump, Valves, Rockshaft, Selective Control Valves and Couplers, Independent Control Valve (ICV) | |
| Frame, Axle and Wheels | Main Frame, Front Axle, Front and Rear Wheels/Fenders, Trailer Mounting/Swinging Drawbar, Triple Link Suspension (TLS) | |
| Operator's Cab | Controls and Instruments, Air Conditioning System, ClimaTrak, Heating System, Seats, Cab Structure, Low-Clearance Cab, Cab Suspension | |
| Special Tools | Dealer-Fabricated Special Tools, Tools Available from the Dealer |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| 6120, 6220 | ||
| Engine (4-cylinder models) | John Deere 4045TL056 diesel | |
| 6320, 6420, 6120L-6520L | ||
| Engine (6-cylinder models) | John Deere 6068 diesel | |
| All models | ||
| Slow idle - mechanical actuation | 875 plus or minus 50 rpm | |
| Slow idle - electronic actuation (above 20 deg C) | 850 plus or minus 10 rpm | |
| Fast idle - mechanical actuation | 2460 +50 rpm | |
| Fast idle - electronic actuation | 2460 -10/+20 rpm | |
| Rated engine speed | 2300 rpm | |
| Engine mounting screws torque | 100 N.m (74 lb-ft) | |
| Front engine supports to main frame torque | 95 N.m (70 lb-ft) | |
| U-joint shaft to input flange torque | 135 N.m (100 lb-ft) | |
| Cooling system test pressure | 50 to 60 kPa (0.5 to 0.6 bar / 7 to 8.7 psi) | |
| Radiator cap pressure valve opens at | 70 to 90 kPa (0.70 to 0.90 bar / 10 to 13 psi) | |
John Deere 6120-6520L Common Problems This Manual Covers
AC compressor clutch cycles on and off continuously with no clear fault
Test the refrigerant pressure sending unit (B130) and the evaporator core temperature sending unit (B129) using the diagnostic flow in the Electrical System section. A failed sender returns a signal that swings the AC clutch relay (K09/4) on and off in short bursts. Replace the faulty sender before condemning the compressor or recharging the system, since the refrigerant level is usually correct.
Manual Section: Electrical System / Operator's CabEngine runs rough at idle or hunts between high and low rpm after reinstall
Check the idle speed adjustment against the specification in the General Information section: mechanical-actuation slow idle is 875 plus or minus 50 rpm, electronic slow idle above 20 deg C is 850 plus or minus 10 rpm. Also verify the hand throttle sensor voltage output is 0.5 to 4.5 V over its full travel. Incorrect idle settings after engine work are a common cause of rough running on the 6020 Series.
Manual Section: General InformationTransmission slips or fails to engage cleanly on upshift or directional change
On PowrQuad and Power Reverser units, check the PowrQuad module or Power Reverser module for solenoid wear and clutch pack condition as described in the relevant Transmission section. On SyncroPlus models, inspect the Perma Clutch II module. Each section covers the module removal, clutch pack inspection and re-assembly procedure so you can confirm whether the fault is electrical or mechanical before ordering parts.
Manual Section: SyncroPlus / PowrQuad / Power Reverser TransmissionHydraulic rockshaft responds slowly or external implement drops when the engine idles down
Low charge pressure from the hydraulic pump or a leaking rockshaft control valve is the common cause on high-hour 6020 Series tractors. The Hydraulic System section covers pressure testing the charge oil pump, inspecting the rockshaft valve and seals, and adjusting the independent control valve (ICV). Work through the pressure tests in the Controls and Valves groups before pulling the pump to confirm the leak location.
Manual Section: Hydraulic SystemFrequently Asked Questions
What transmission types does this manual cover for the John Deere 6120 to 6520L?
It covers all four transmissions offered on the 6020 Series: SyncroPlus, Power Reverser, AutoPowr/IVT and PowrQuad/PowrQuad Plus/AutoQuad. Each has its own section with removal, module disassembly and shift-control adjustment procedures, so you work on the exact transmission your tractor has.
What are the engine idle and rated speed specs for the John Deere 6120/6320/6420?
Slow idle is 875 plus or minus 50 rpm with mechanical actuation, or 850 plus or minus 10 rpm electronically above 20 deg C. Fast idle is 2460 rpm. Rated engine speed is 2300 rpm. These are the adjustment targets in the General Information/Specifications section, not the programmed ECU limits.
Why does the AC compressor on a John Deere 6420 cycle on and off constantly?
The usual cause is a failed refrigerant pressure sending unit (B130) or evaporator core temperature sending unit (B129) giving a false reading that triggers continuous clutch cycling. The Electrical System and Operator's Cab sections cover testing the sending units and the AC relay (K09/4) before replacing the compressor.
What torque specs does this manual give for engine installation on the 6020 Series?
Engine mounting screws torque to 100 N.m (74 lb-ft). Front engine supports to main frame cap screws torque to 95 N.m (70 lb-ft). U-joint shaft to input flange cap screws torque to 135 N.m (100 lb-ft). All are listed in the General Information specifications section.
Does this repair manual cover the front-wheel drive axle and Triple Link Suspension on 6120L to 6520L models?
Yes. The Miscellaneous section covers the front axle, front-wheel drive clutch and differential. Triple Link Suspension (TLS) is covered with its own group including the TLS cylinder and frame. The Drive Systems section covers the front-wheel drive clutch separately from the axle assembly.
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